The potassium channel opener BRL 38227 inhibits binding of [125I]-labelled endothelin-1 to rat cardiac membranes. |
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| Authors: | C J Waugh M E Dockrell W G Haynes H J Olverman B C Williams D J Webb |
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| Institution: | Edinburgh University Department of Medicine, Western General Hospital. |
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| Abstract: | Binding of 125I]-labelled endothelin-1 (ET-1) to rat cardiac membranes and the effects of endothelin-1 (ET-1), endothelin-3 (ET-3), the calcium channel antagonist nifedipine, and both enantiomers of the potassium channel opener cromakalim (BRL 34915) on binding have been examined. Specific binding of 125I]-ET-1 was inhibited in a concentration dependent manner by both unlabelled ET-1 (10(-12)-10(-7) M) and ET-3 (10(-12)-10(-6) M). Nifedipine (10(-11)-10(-5) M) did not affect 125I]-ET-1 binding. However, BRL 38227 (10(-11)-10(-5) M), the biologically active isomer of cromakalim, significantly inhibited 125I]-ET-1 binding. The inactive isomer, BRL 38226 (10(-11)-10(-5) M) had no effect. These findings provide the first evidence for a stereospecific interaction between BRL 38227 and an ET-1 binding site in rat cardiac membranes. |
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